* {
  padding: 0;
  margin: 0;
}

#app {
  width: 100vw;
  height: 100vh;
}

.layer {
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 500px;
  height: 500px;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  background-color: rgba(0, 0, 0, .7);
  z-index: 999;
}

.startBtn {
  display: block;
  width: 70px;
  height: 70px;
  line-height: 70px;
  text-align: center;
  border-radius: 50%;
  color: rgb(209, 19, 19);
  background-color: beige;
  cursor: pointer;
  user-select: none;
  font-size: 14px;
}

.restart {
  width: 75px;
  height: 75px;
  line-height: 75px;
  text-align: center;
  color: rgb(209, 19, 19);
  background-color: beige;
  cursor: pointer;
  font-size: 14px;
  border-radius: 50%;
  user-select: none;
}

.tips {
  position: absolute;
  display: block;
  width: 250px;
  height: 50px;
  text-align: center;
  line-height: 50px;
  background-color: #Fff;
  color: rgb(221, 90, 90);
  font-size: 14px;
  transform: translateY(-200%);
  user-select: none;
}

.puzzle {
  position: absolute;
  border: 2px solid #ccc;
  margin: 0 auto;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

.block {
  box-sizing: border-box;
  position: absolute;
  border: 1px solid #fff;
  transition: all .3s;
}